P2CF2Auxiliary Thermostat B Stuck Closed
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- Needs a drive cycle to confirm a fix
- How the car detects it
- P2CF2 is logged when auxiliary thermostat B does not open: the temperature in its loop keeps rising beyond the opening point while the controller expects it to level off. The loop assigned to B differs by maker, so the actual consequence can be an overheating cylinder head, hot engine oil or, if B guards a smaller branch, merely a local hot spot that the main gauge does not show. No manufacturer documents P2CF2 publicly; for thermostat A on the four-cylinder Lotus Emira the published check is whether the piston extends in hot water, and the same test applies here. Wax thermostats fail closed mainly through a leaking wax charge or a jammed piston. CARB covers systems with several thermostats under its cooling monitor. Treat it as an overheating risk.
- What you may notice
- Engine warning lamp
- Overheating warning or high oil temperature
- Reduced power to protect the engine
- Likely causes
- LikelyLeaking wax charge, thermostat stays shut
- PossiblePiston seized by corrosion or deposits
- RareTemperature sensor of that loop reading too high
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Medium · Usually a job for a workshop.Typical cost: €120 – €800
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.